This came out of this question when discussing in the comments what is and is not allowed.
For some context, David Coffron said in the comments of the above question:
[...] Does unofficial, published content (i.e. 3rd party content) count for your question? [...]
[... I answered with basically "what even is XGtE Expanded Racial Feats?" ...]
[...] It does have WoTC approval (according to the document itself), but I don't think its considered official. Bit of a weird case. XGtE is an official book, but the expanded feats are not MWICT.
So, does the XGtE Expanded Racial Feats have WotC's approval, is it considered official or unofficial, 3rd party or what? What is it exactly?